Immigration raids have seen a sharp rise since 2010, when current Prime Minister Theresa May became home secretary, with around 11 round-ups taking place every day in London alone.

According to data obtained through a freedom of information (FoI) request to the Home Office, workplace raids increased by 80 percent between 2010, when the Conservatives returned to power, and 2015.

The capital was the focus of most of the UK Border Agency’s (UKBA) missions, but unannounced checks also took place in Wigan, Greater Manchester and Berwick-Upon-Tweed, Northumberland.

Earlier this month, London employees of burger chain Byron were called for a health and safety training meeting which turned out to be an immigration swoop. A total of 35 people were arrested on suspicion of breaking immigration laws, including Albanian, Brazilian, Nepalese and Egyptian nationals.

“They have a rhetoric in which immigration is threatening, they have a narrative in which the public want to see the government be tough and raids are a way to have numbers [and] show results.”

New amendments to the Immigration Act mean it is now a criminal offense to work without a valid permit. Penalty fines doubled from £10,000 to £20,000 (US$13,100 to $19,700) and the prison sentence attached went from two to five years.

Businesses can also be shut for up to 48 hours if they cannot prove that migration status checks were done before hiring.

“The main effect of that is wages are regarded as the proceeds of crime and it actually becomes possible for the immigration authorities to confiscate any money that they find in [a migrant’s] possession if they feel that that has come as the product of working,” Flynn explained.

“We argue that is totally and completely disproportionate.

“In an area like London, where 40 percent of the employed population were born abroad and where immigration is not a black or white issue, it’s not like you can easily divide the world into people who are legally entitled and people who are not. There is a huge gray area of people who are legally resident in the country but their entitlement to enter the labor market is covered by an immensely complex raft of regulations of one sort or another.”

Migrants’ Rights Network has seen employers respond in one of two ways: they either opt not to employ “anybody who looks foreign,” which effectively adds up to discrimination; or they use workers’ vulnerability to exploit them.

“You will find it difficult to convince people that you’re entitled to work, they’ll take you on but the hourly rate will drop by £2, and if you complain about anything, you are out the door immediately,” is often an employer’s cynical line, says Flynn.

Byron confirmed it had “cooperated fully” with the UKBA on its latest raid, but did not comment on the pretexts it had used to ambush staff. In a statement, the burger chain said it had complied with employment regulations, but the relevant documentation of some of its migrant workers had been “false/counterfeit.”

Boycotting Byron, however, is not the solution to the problem, Flynn said.

“I’d like to see the trade unions get into Byron at some point, surely there must be a lot of angry employees at that company at the moment. This might very well be an opportunity to get them all [organized]. That might be the best response, for the Byron workers coming out saying, ‘Hey these are our workmates, we’ve been working with the for the last four or five years, we are extremely indignant about this, about bad employment practices.’”

Data collected by Migrant’s Rights Network also shows that not all immigration raids take place on the right side of the law. In 2014 a report published by the Chief Inspector of Borders & Immigration stated that up to two-thirds of swoops actually abused or misused the power to enter premises.

Other well-known companies to have recently jumped their workers with surprise immigration status checks include take-away service Deliveroo and fast food giant McDonald’s.

A protest outside Byron’s Holborn branch has been called for Monday, August 1 by unions, migrant networks and human rights charities, and will be hosted in solidarity with the chain’s arrested workers. More than 1,000 people are expected to attend.